Pall SepraSol™ Liquid/Gas Coalescer Offers Quick Return on Investment; Recovers Carried-over Glycol

A major producer in Texas operates a 50 MMSCFD conditioning plant for processing gas to sales gas. The conditioning plant, as shown in Figure 1, sweetens the gas, dries it, with the resultant clean, dried stream sent forward as sales gas.

Figure 1. Conditioning Plant Schematic

Problem Areas

The glycol unit, in this plant, was experiencing severe glycol carry-over problems in the range of 0.5 - 0.7 gallons/MMSCFD. The operator and dehydration vendor could not solve the carry-over problem, which amounted to 25 gallons per day or over 9000 gallons of glycol per year lost with the sales gas. Also, glycol was being continually added to the system.



The operator then installed a Pall SepraSol™ Liquid/Gas Coalescing Filtration System downstream of the glycol dehydration system in order to recover the carried-over glycol. The SepraSol Coalescing Filter Assembly removes glycol as well as other liquids and solids to an effluent level of less than 0.01 ppm with 99.98% removal of all aerosols 0.3µm and larger. Pall studies indicate that most of the aerosols in a gas stream are between 0.1 - 0.6µm in size. The LG Coalescer, because of its 0.3µm absolute rating, coalesced and removed these size droplets. The operator has only found liquids in the upper sump, which confirms Pall's studies and proves that the LG Coalescer removal efficiency is accurate. The vessel containing 12 SepraSol Coalescing elements (part number CC3LGA7H13) was installed for a flow rate of 50 MMSCFD at 700 psig.



The SepraSol Coalescer installation allowed the operator to recover and to reuse the carried-over glycol. The glycol, from the upper sump, is drained directly into the flash tank prior to the reboiler. As shown in Table 1, the direct savings to the operator was approximately $26,000 resulting in payback in less than one year. The SepraSol Liquid/Gas Coalescing Filter Assembly was operating at its initial differential pressure of 3-4 psid, after twelve months in service.

Table 1. Actual Economic Benefits
Problem Total Savings Per Year1
Glycol loss from contactor of 0.5 gallons/MMSCFD from a 50 MMSCFD unit $26,280
(1) Assuming glycol costs 0.36/lb